thank you. I have another question: is there any difference in meaning between "they were meeting secretely after school" and "they met secretely after school" for example yesterday, every week, etc. Is it possible to use either past simple or past continuous in this example, without difference in meaning?

The context would determine which form you should use here. For example, if you're just speaking about a routine habit all last year, the past simple would probably be the best. But imagine, for example, that you thought your daughter had been going to her friend's and her boyfriend to his job after school, but just found out that they'd been meeting. In this case, by saying 'They were meeting secretly' as you were explaining it to your partner, their meetings weren't just a routine habit for you -- they were something you don't approve of that happened again and again in that particular time period. Using the past continuous helps communicate this.

That, of course, is just one situation -- there are an infinite number of other ones that could call for the use of the past continuous or the past simple.

could it be that "I was practising" every day is used because you find it annoying,because you didn`t want to practise and "I practised every day" is neutral? I am asking, because present simple is used for habits, and doing something every day is a habit. That is what I don`t understand. Same goes for "i have been watching the programme every week", is it because it is a temporary habit that the past continuous is used? Why can`t you say "I watch it every week", if the programme has been broadcast for years, like Eastenders for example. I have read the page on the continuous aspect, but i am still not sure.

The continuous aspect can be used to communicate different meanings, and yes, one of them is of something temporary, and sometimes this temporary thing can be something we don't or didn't enjoy. It's not that 'I practised every day' can't communicate annoyance -- you could communicate with a certain tone of voice, for example -- but by itself it is neutral, whereas the continuous form shows that there's an additional layer of meaning.

Similarly, 'I've been watching it every week' could express different meanings, one of which is that it's something temporary. For example, perhaps you used to watch it once or twice a month, but now that you plan to go to university in London, you're watching it more often to get used to the accent.

i have a question regarding something happening again and again: what is the difference between "I was practising every day, three times a day"and "I practised every day", since the past simple is used for regular habits. The same goes for "I have been watching the programme every week", is it possible to say "I watch the programme every week" without difference in meaning.

The continuous aspect changes the way that we see a particular action or group of actions. The meaning it adds is dependent on the situation. It can show that an action is repeated or that it is (was/will be) in progress around a certain time, for example. For more detailed descriptions of this and examples please take a look at this page. Try to apply the information there to your examples and explain them yourself, and we'll be happy to comment on your explanations if you put them in the comments.

Hi,
While I was leaning English grammar, I met a sentence as below:
- I know Doug was working late at the office because I saw him when I was leaving.
I don't understand why past continuous tense is used for the 'work' verb ('was working'). In my opinion, it should be past simple tense ('worked').
Please help me explain it in detail.
Thank you!
Best,
David

You could say 'worked' and it would also be correct. It depends on what you mean to say, but in general the past simple would simply indicate that you saw Doug at the office after hours whereas the past continuous could be used to emphasise that you saw the working in progress. This could be appropriate, for example, when a friend of yours says that she saw Doug at a restaurant at the same time you saw him at the office.

Good evening.
I'm a little bit confused about this part
*(we use past continuous) for something that was happening again and again:
1.I was practising every day, three times a day.
what about this one is this correct ?
2.Last year,I was going to the cinema every weekend.